> Let say my project is at revision 905 and I want to revert changes
> on two files. So I check out revision 900 of those files. But how
> do I commit the files now as HEAD revision? Because there are no
> changes, subversion does not want to submit the files!?

You can you svn merge with argument -r 905:900 on the chosen files,
so svn will apply to rev. 905 of these files the patch that revert
them from r905 to r900.